It is frequently desirable or advantageous to treat the surfaces of a variety of substrates, such as fabrics, skin, and hair, with benefit agents; exemplary benefit agents include perfumes; flavors; pharmaceuticals or bio-control agents, such as biocides, insecticides, and mildew control agents; and the like.
Products, systems and methods for depositing benefit agents onto the surfaces of substrates are well known in the art. For example, in the context of fabric treatment, including fabric laundering, a variety of laundry and other products exist that can be used to form aqueous washing liquors or rinse baths containing benefit agents; upon contact with the liquors or baths, the benefit agents are deposited onto the fabric. Personal care products also exist that deliver, in a similar manner, benefit agents to substrates, such as skin and hair. These laundry, personal care, and other products can be applied directly to the surface of the substrate as leave-on products or wash-off products. In either product format, the objective of using these products in substrate treatments is to deposit sufficient benefit agents on the substrate surface so that the substrate surface exhibits a residual or longer lasting benefit after treatment of the substrate is completed.
In addition, in many consumer products, it is desirable for certain benefit agents, such as perfume raw materials, to be deposited more effectively on the surface and/or released in a controlled manner over time. Since the most volatile perfume raw materials, referred to as “top notes” are responsible for the “fresh feeling” consumers experience, it is especially desirable for the more volatile top notes to be deposited more effectively and/or released in a controlled manner over an extended period of time.
Since top notes are conventionally lost due to dissolution and/or evaporation in aqueous media, formulators have tried to minimize the loss of top notes by exploring technologies that enhance the deposition of top notes on substrates, even when the substrate is immersed in or treated with copious amount of water and/or when the substrate subsequently is exposed to atmospheric moisture. Even when directly deposited on substrates, there still remains a need to release the perfume raw materials in an extended, controlled manner.
Prior art attempts disclose the use of pre-loaded perfume polymeric particles to aid the deposition of perfume raw materials onto surfaces and/or control the release of perfume from surfaces. Such attempts include matrix systems in which the fragrance is dissolved or dispersed into the polymer matrix, as well as reservoir system in which the fragrance is surrounded by a rate controlling membrane. Other attempts have included polymerizing the perfume raw materials into a polymer particle or absorbing perfume into polymer particles. These systems are “pre-loaded perfume polymeric particles”. Details of these attempts are described in U.S. Pat. No. 6,149,375; WO 98/2839; WO 00/68352; WO 01/79303 and EP 925,776.
Formulators have been less than successful in efficiently depositing perfume raw materials, especially top notes, onto substrates using pre-loaded perfume polymeric particles. Without being bound by theory, the lack of efficiency can be due to reduction or loss of the interaction between the benefit agent and the delivery system during in-product storage. For example, the interaction between perfume and polymer particle can be lost via uncontrolled diffusion of perfume raw material from the pre-loaded perfume polymeric particles into the product matrix or atmosphere. Such loss is quite common under the storage conditions consumer products typically experience.
Attempts to stabilize the pre-loaded perfume polymeric particles to in-product diffusion have resulted in limited success. Attempts to increase stability can be accompanied by undesirable changes in the rate of release of the benefit agent from the delivery system.
Notwithstanding the advances in the art, there remains a continuing need for better benefit agent delivery systems, especially those delivery systems that are effective for delivering residual and long-lasting benefit agents to substrates treated with such delivery systems.